Ping-Shou Cheng

Improvements in the sintering and microwave properties of BiNbO4 microwave ceramics by V2O5 addition

Abstract The effects of V2O5 on the phase formation and the microwave dielectric properties of BiNbO4 ceramics were investigated as a function of the amount of V2O5. As the amount of V2O5 addition increased from 0.125 to 1 wt%, the densification temperatures of BiNbO4 ceramics decreased from 960 to 900°C. For densified BiNbO4 ceramics, as the amount of V2O5 increased from 0.125 to 1 wt% V2O5 added, the dielectric constants decreased from 43.7 to 43.4 and the temperature coefficients (τf) increased from +2.8 to +19.5 ppm/°C. The quality values (Q) of V2O5-doped BiNbO4 ceramics first increased, reached a maximum at 0.5 wt% V2O5, and then decreased with the further increase amount of V2O5 addition. The 0.5 wt%-V2O5-doped BiNbO4 ceramics sintered at 960°C had the optimum microwave dielectric properties: er=43.6, τf=+13.8 ppm/°C, and Q=3410.

Substitution of CaO by BaO to improve the microwave dielectric properties of CaO-Li2O-Sm2O3-TiO2 ceramics

Abstract Sintered CaO–Li 2 O 3 –Sm 2 O 3 –TiO 2 (16:9:12:63) composition (CLST) at 1325°C shows microwave dielectric properties: e r =104.1, Q ∗ f value=4320 GHz, and τ f =13.2 ppm/°C. When BaO is used to substitute CaO in the CLST composition to form CaO–BaO–Li 2 O–Sm 2 O 3 –TiO 2 =16− x : x :9:12:63 ( x =2 and 4 for CBLST2 and CBLST4), the sintered CBLST2 and CBLST4 ceramics show coexistence of two phases, the perovskite CaO–Li 2 O 3 –Sm 2 O 3 –TiO 2 (CLST) phase and BaSm 2 Ti 4 O 12 (BST). As the BaO content increases from 0 to 4 mol%, the dielectric constant of CBLST ceramics decreases from 104.1 to 94.5, the Q ∗ f value increases from 4320 to 6740, and the τ f value changes from 13.2 to 3.24 ppm/°C.

Nullor Equivalents of Active Devices for Symbolic Circuit Analysis

The new pathological elements, the voltage mirror (VM) and current mirror (CM), have shown advantages in analog behavioral modeling and circuit synthesis. Recently, the floating mirror elements have been used to derive pathological sections to ideally represent various popular analog signal processing properties that involve differential or multiple single-ended signals. In order to take advantage of the symbolic nodal analysis (NA) of nullor-mirror networks, we present the nullor equivalents of a differential voltage cell, a differential voltage conveying cell, and a current replication cell in this paper. The proposed nullor equivalents can be used to represent many popular active devices in performing symbolic NA. Two representative filter circuits containing differential characteristics of active devices are given to verify the feasibility. We expect them to be used within an analog design automation environment to enhance circuit analysis and modeling.

Microstrip-fed printed dipole antenna for 2.4/5.2 GHz WLAN operation

In order to satisfy the 2.4 GHz band of IEEE 802.11b and the 5.2 GHz band of the IEEE 802.11a WLAN standard, dual-band operation in the 2.4 GHz (2412-2484 MHz) and 5.2 GHz (5150-5350 MHz) bands are demanded in practical WLAN applications. A new microstrip-fed dual frequency printed dipole antenna is presented. With an inverted-L slit embedded into both arms of the dipole, a dual-band operation is generated in a single antenna. The proposed design does not require separate dipole arms to achieve two separate operating bands, and it has a shorter length of arm than the design in Suh et al. (2000). The proposed antenna can easily be excited by a 50-/spl Omega/ microstrip line and a pair of parallel metal strips between the dipole and the microstrip line, and good impedance matching can be obtained for operating frequencies within both 2.4 and 5.2 GHz bands.

The Effect of the Crystalline Phase on the Sintering and Microwave Dielectric Properties of CuO-doped(Bi0.95Sm0.05)NbO4 Ceramics.

The crystalline phase and the microwave dielectric properties of the 0.5 wt%-CuO-added (Bi0.95Sm0.05)NbO4 ceramics are developed. The intensity of the low temperature form of the (Bi,Sm)NbO4 (α-form) first increases, reaches a saturation value at 1000°C, and then decreases with the increase of the sintering temperature. The α-form (Bi,Sm)NbO4 disappears at 1040°C, the high temperature form of the (Bi,Sm)NbO4 (β-form) starts to appear at 980°C and then the intensity of the β-form (Bi,Sm)NbO4 increase with the increase of the sintering temperature. The dielectric constants (er) show no apparent change but the quality values (Q×f) first increase, reach a maximum at 1020°C, and then decrease with the increase of the sintering temperature. As the sintering temperature increases from 1020°C to 1040°C, the temperature coefficients (τf) critically change from -15.1 ppm/°C to -203.5 ppm/°C.

The reaction sequence and dielectric properties of BaSm2Ti4O12 ceramics

Abstract To establish the correct reaction sequence of BaO–Sm 2 O 3 –4TiO 2 , phases present in different calcining temperatures are identified by X-ray diffraction patterns. When different calcining temperatures are used, the source phase BaO (BaCO 3 ) consumes below 850°C, the source phases TiO 2 and Sm 2 O 3 consume at 1000 and 1150°C; the intermediate phases BaTiO 3 , BaTi 4 O 9 , and Sm 2 Ti 2 O 7 consume at 1050, 1200, and 1250°C, respectively. The BaSm 2 Ti 4 O 12 phase starts to reveal at the 1100°C-calcined powder. The integrating intensity of BaSm 2 Ti 4 O 12 phase increases with the raising of calcining temperatures, accompanying with the decrease of integrating intensities of the source and intermediate phases. As the sintering temperature increases, the densities, quality values, and dielectric constants of BaSm 2 Ti 4 O 12 ceramics increase and saturate at 1325 o C. The BaSm 2 Ti 4 O 12 ceramics sintered at 1325°C have the properties of Q ∗ f=5180,e r =81.8 , and τ f =−19.2 ppm/°C.

An embedded wavelet image coding algorithm and its hardware implementation based on zero-block and array (EZBA)

In this paper, we first propose an embedded wavelet image coding algorithm based on zero-blocks and array structures - called EZBA. Then, we discuss the hardware realization of the algorithm. In comparison with other methods, the EZBA is simpler to be realized and has higher compression efficiency. For hardware realization, we implement two main parts. One is the discrete wavelet transform (DWT); the other is the architecture of retrieving and coding algorithm (the EZBA itself). Experimental results show that the proposed EZBA outperforms other wavelet-based image coding schemes.

Improvement of Sintering and Microwave Dielectric Characteristics of Ba(Mg1/3Ta2/3)O3 Ceramics by Addition of BaTi4O9

BaTi4O9 (BT4) calcined at 1150°C and Ba(Mg1/3Ta2/3)O3 (BMT) calcined at 1200°C are mixed, the sintering and the microwave dielectric characteristics of 0.18 mol BT4 and 0.82 mol BMT ceramics are determined (BT4-BMT). The required sintering temperature of BT4-BMT ceramics is decreased to approximately 1320°C. As the sintering temperatures increase from 1240 to 1360°C, the microwave dielectric properties of BT4-BMT ceramics change as follows: The er values increase from 23.5 to 28.0, the Q*f values increase from 25200 to 64700 and the τf values linearly change from 2.0 ppm/°C to 4.3 ppm/°C. The er values, the Q*f values and the τf values are saturated in 1320°C-sintered ceramics.

A Novel Calcining Method Used to Fabricate the K0.5Na0.5NbO3 Ceramics

K0.5Na0.5NbO3 ceramic prepared by a conventional solid-state reaction process (calcinated at 850°C and sintered) is so fragile that it can not be used to measure dielectric properties. In this paper, we use a two-step calcining method to synthesize KNN composition, with a hydrothermal treatment (200°C for 4 hrs) preceding the calcining process (750°C and 850°C for 2 hrs). Following the hydrothermal treatment and calcining the KNN ceramic was sintered at 1100°C ∼ 1160°C. X-ray diffraction patterns for all KNN ceramics showed a perovskite structure with orthorhombic symmetry. The effects of different calcining and sintering temperatures on the properties of the resulting KNN ceramic, including surface morphology and dielectric characteristic, were recorded and analyzed.

A fuzzy system for evaluating radiation treatment plans of head and neck cancer

In this study, 14 treatment planning dose parameters for head and neck cancer are adopted as the characteristic functions to establish the statistical analysis of the fuzzy system module for radiation treatment plan classification. By constructing fuzzy rules and fuzzy set membership functions, we aim to improve the classification efficiency and accuracy by the fuzzy systems, and to improve the quality of the treatment plan. Three different fuzzy logic control systems were used for analysis of 100 Pinnacle treatment planning system datasets. The results show that the accuracy may be up to 100%. The fuzzy logic control system we propose may be a useful tool for accurate planning and decision-making.